I'm just constantly tired, even after a good long sleep and i've recently been over eating and eating high sugared food. why is this?

Get checked !: It's very common for people to reach for high energy but bad-for-you foods when they are exhausted. You need to find out why you are tired. Could be thyroid, anemia, kidney or liver disease, diabetes... So many things. Get a general check up. If no cause is found, see a functional medicine doctor. Look here: http://www.Functionalmedicine.Org/practitioner_search.Aspx?Id=117.